"Never let a chance go by," Wilson Mizner urges his brother Addison. "Now and then you miss one, but I guarantee you this one is a winner." Addison has just struck the mother lode, literallygold nuggets in the Yukon! But Wilson sees a greater opportunity around the corner, and trades away their gold claim over a hand of poker. That's the story of the Mizner brothers: Every time they get a leg up, they find a way to squander it.

It's also the feeling you get watching Road Show, the long-gestating musical written by Stephen Sondheim (music and lyrics) and John Weidman (book). Ten years after the New York premiere of the final version, Road Show finally makes its New England debut at Lyric Stage Company. But the much-anticipated show never gives us much insight into these two brothers, or why we should care about their long list of disappointments.

The show opens at the end: Addison Mizner is dead, and his old business partners and ex-lover mourn him by telling us his life was a complete waste. As we flash back to the younger Addison and Wilson, both determined to make their mark in the world, we understand what the chorus was singing about. The boys strike gold, then gamble it away. Addison travels around the world, but all his business ventures fall through. Wilson marries a wealthy dowager and fritters away her money. It's an endless cycle. When Addison falls in love with the young Hollis Bessemer, a playboy cut off from his father's wealth, his luck finally looks up. But sure enough, Wilson comes back on the scene with one last con job.

Sondheim's last finished score (for now) is probably the main reason theatergoers will be interested in Road Show. The development of Sondheim and Weidman's musical, including an earlier version called Bounce (and, before that, Wise Guys), has been well documented. The composer embraces the jaunty old-fashioned Broadway style he sometimes eschews, but he burnishes that sprightly Americana sound with darker hints of disenchantment. Fans will notice many similarities to his music for Assassins . But while Sondheim-as-lyricist clearly delights in the clever patter of prospectors, socialites and racketeers, the constant musical montages quickly become repetitive. Every time the chorus appears to sing a new number, we know things will fall apart by song's end.

Clocking in at a swift ninety minutes, the show moves quickly from one failure to the next, without much time to reflect. Weidman provides minimal dialogue between songs, so it often feels like the connective tissue is missing. And Lyric Stage's production never lands on a coherent tone to smooth out the bumps in the material. As co-directed by Spiro Veloudos and Ilyse Robbins, the characters swing between naturalism and broad caricature. Should we take these brothers' ambitions ironically, or at face value? Aspects of the press performance felt under-rehearsed, including the cast's wandering harmonies and some difficulties projecting lyrics over the small orchestra.

Ultimately, Road Show tries to deconstruct the complicated bond between its two brothers. Tony Castellanos as Wilson, the younger Mizner, has plenty of flim-flam showmanship. He's the devil on your shoulder, the ultimate snake charmer. But Castellanos doesn't find much dimension behind the huckster facade. It's hard to figure out why Addison wants to be anywhere near him. Neil A. Casey, on the other hand, really makes us feel for Addison. Casey finds the right balance between his character's good intentions and his darker impulses, convincing in his relationship with Patrick Varner's Hollis, then reverting to childlike resentment around Wilson. He gives the show some needed weight, suggesting (in his wearied expression and gruff singing voice) the emotional toll of every get-rich-quick scheme he's sucked into.

It's in the spaces between these schemes where we see what Road Show could have been. The sweetness of Addison and Hollis's romance, in particular, brightens the second half of the show. We finally see a glimpse into their inner lives. Their duet, "The Best Thing That Ever Has Happened," is the stand-out of the scorea rare straightforward love song from Sondheim, delivered winningly by Casey and Varner. To echo Sondheim's lyric, now and then you miss one, but there are hints of a first-rate show glistening beneath the surface.

Road Show is presented at The Lyric Stage Company of Boston through February 11, 2018, at 140 Clarendon Street, Boston MA. Tickets can be purchased at lyricstage.com, by phone at 617-585-5678, or in person at the Lyric Stage box office.